Tooltip placement algorithm

[JobLeonard]

This looks promising, and it has a JS library too! "All" we need is a way to convert the points to a polygon: https://www.mapbox.com/blog/polygon-center/

[JobLeonard]

https://en.wikipedia.org/wiki/Alpha_shape

https://www.npmjs.com/package/alpha-shape

https://mikolalysenko.github.io/alpha-shape/index.html

Probably not scaling to hundreds of thousands of points, but still interesting

[JobLeonard]

https://github.com/AndriiHeonia/hull

[JobLeonard]

So I've been checking Delaunay libraries for JS (it's the typical kind of thing where you hope someone implemented a robust library for you), since it looks like we're going to need one.

I suspect this is the best option:

https://www.npmjs.com/package/delaunator

Four reasons:

• it was recently updated
• it has been tested up to a million points, so probably is robust:
• it compares itself to all other Delaunay libraries for JS, so it's properly battle-tested, should scale to our needs (and hopefully has stolen good bits of performance tricks from all over the place)
• it cites multiple scientific papers on DT algorithms, so the authors did their homework